兰州远郊区黑碳气溶胶浓度特征

Property of black carbon concentration over outskirts of Lanzhou,Northwest China

利用兰州大学半干旱气候与环境观测站(SACOL)2007年1月1日至2009年8月28日黑碳气溶胶浓度和同期常规气象资料,分析了兰州远郊区黑碳气溶胶浓度特征.结果表明,该区黑碳气溶胶日平均浓度为1568ng/m3,低于东部地区区域本底站浓度,表明该地区污染较轻;黑碳浓度具有明显的季节变化,从春季到冬季平均浓度依次增大,分别为1234.74,1290.23,1669.06,2088.73ng/m3,日变化具有明显的双峰结构,最大值出现在09:00,最小值出现在17:00.黑碳浓度的变化特征与本地区的盛行风向、人类活动及天气过程有密切关系.沙尘气溶胶对黑碳浓度的影响取决沙尘过程的强度、沙尘携带的人为污染物的种类及数量、黑碳颗粒被其他气溶胶混合和包裹的程度.统计分析得出该地区大气黑碳气溶胶本底浓度约为1000ng/m3.

The characteristics of black carbon（BC） concentration were analyzed using the BC monitoring data of Semi-arid Climate Observatory and Laboratory（SACOL） during the period from January 2007to August 2009.The average daily BC surface concentration was 1568ng/m^3,lower than that of some background observation stations in East China.The BC concentration obviously had a seasonal variation from spring to summer,autumn and winter,with respective value of 1234.74,1290.23,1669.06 and 2088.73ng/m^3.The diurnal variation showed a bimodal distribution with the maximum value at 09：00（Beijing Time）,and the minimum at 17：00.The variation of BC concentration was closely related with the air pollution emission and diffusion condition.The affection of dust events to BC concentration depended on the strength of the dust events,the type and the amount of the anthropogenic aerosols captured by the dust particles,and the mixing state of BC particles with other aerosols.According to the data statistical analysis the BC surface background concentration at SACOL was 1000ng/m^3.